Safire, William (1988-09-25), “On Language: 'Eat Your Peas'”, in The New York Times‎[1], The New York Times Company "Def, a clip of definitely is now the word for terrif, and on some campuses has out-neatened neat."

Brent, Staples (1988-12-18), “On Language: 'High on the Five'”, in The New York Times‎[2], The New York Times Company " Failing to see the word's antecedents, I suspected that def was either bogus or an orphan, lost to its slang ancestors through mispronunciation or misspelling... Three critics of popular music failed to provide me with satisfactory antecedents. One suggested that def was an abbreviation of definitely, another suggested deference and the third had no hunch at all... Russell Simmons, a founder of the company [Def Jam Recordings], said that his partner, in designing the logo for the company's record label, may have been the first to set def down in writing. Simmons also said that his associate had clearly misheard the word as it was then spoken in the streets. Def, Simmons said, was a mispronunciation of death."